Most of the larger pleasure and general fishing boats sold for non-commercial uses in the 16 to 24 foot range are provided with stern drive units, also called inboard/outboards, wherein the motor is within the boat hull, with a drive train extending through the transom to a stern-mounted drive unit carrying the propeller. While these stern drive units are capable of propelling the boat at a relatively high speed efficiently, it is either impossible, or very inefficient, to utilize such a motor to move the boat for long periods of time at very slow speeds, such as when trolling for fish. For this reason, many of these boats are provided with an auxilliary outboard motor, having considerably less horsepower and being much more efficient and inexpensive to operate when the boat is to be moved slowly.
The typical stern drive unit may be operated in a lower position with the propeller in the water, or the entire drive unit exterior of the boat hull may be tilted upwardly to remove the propeller from the water, thereby causing less drag when the smaller outboard motor is utilized. In order for the propeller of the outboard motor to reach beneath the water's surface, the outboard motor must be mounted to the boat transom below a level which would permit the boat owner to steer the motor with a conventional outboard motor handle extending across the rear gunwale. Therefore, it is advantageous to have an attachment which will permit the driver of the boat to utilize the boat's steering wheel which to steer the outboard motor when it is to be used. This attachment should permit the driver of the boat to steer the outboard motor with the steering wheel when the stern drive unit is in either the upward, non-operative position, or the lower operative position.
The problem encountered when using such a remote steering device when the stern drive unit is tilted upwardly, is that the end of the remote steering device affixed to the stern drive unit not only describes an arc as it moves with the stern drive unit, but also experiences a rotational movement about its longitudinal axis which, unless the device is permitted to rotate about its longitudinal axis, imparts significant twisting strain to the device leading ultimately to its failure.
Devices which permit an auxilliary engine to be controlled from a primary engine are well known in the prior art. U.S. Pat. No. 3,756,186, Nordling, illustrates an attachment which permits an outboard motor to be steered from a stern drive unit. The connecting mechanism includes a pair of telescopic members, each of which is connected through a universal joint to the outboard motor or the stern drive unit. A locking mechanism in the form of a pin extending through openings in both telescopic members is utilized to lock the telescopic members in any desired position depending upon the distance between the stern drive unit and the outboard motor. U.S. Pat. No. 3,567,164, Hakala, shows a support means which permits two outboard motors to be pivotally mounted thereto, so that an auxilliary outboard motor may be conveniently moved to a selected vertical position in water. U.S. Pat. Nos. 3,283,738, Nelson, 2,968,192, Fletcher, 2,899,833, Prier, and 2,744,418, Weber, all illustrate coupling or steering devices which permit a pair of outboard motors to be steered at the same time. U.S. Pat. No. 2,972,976, Smith, illustrates yet another device which permits a pair of stern drive units to be operated concurrently, or a single unit to be operated while the other is tilted or raised out of the water.
U.S. Pat. Nos. 4,009,678, North, 3,505,971, Dalke, and 3,473,764, Hopper, illustrate attachments to boat motors revealed in a patentability search, but which are not considered relevant to the present invention.